-y

If the crystallites first become firmly clamped to the substrate at a thickness of about 2 nm, then the limiting value for the intrinsic stress generated will be of order — 1 GPa. This example illustrates how surface stress effects can explain the compressive stresses often observed during the island growth of non-epitaxial metal films. (Surface stress effects may also explain the origin of compressive stresses often observed in fully grown, continuous metallic and dielectric films [17].) A more complete analysis would include the contribution of the surface stress of the curved surface of an island that, at coalescence, becomes transformed into a grain boundary. This contribution leads to interesting effects that are discussed elsewhere [17].